There are times when a puzzle is so difficult, it is unable to be solved by the majority of those who look at it. They may stare at it for several minutes, but the solution is still not going to present itself.
It’s not because it doesn’t exist, it is a combination of being an optical illusion and, perhaps, being so simple that is just eludes us.
There is something wrong with the image below and many people were unable to find it in under 5 seconds. Even if they have 10 seconds, a large group of people still struggle to solve the puzzle.
Take a look and see how long it takes for you to find the error. You can find the solution on the next page.